iSCSI initiator driver beta version, testers wanted

[Scott Long]

Danny Braniss wrote:
>>Scott Long wrote:
>>
>>>Danny Braniss wrote:
>>>
>>>
>>>>>with tags enabled, iSCSI is much faster, but it also causes a 
>>>>>deadlock :-(
>>>>>this is what i run:
>>>>>    newfs -U /<iscsi device>
>>>>>    cd /<iscsi device>
>>>>>    restore rf /home/file.dump
>>>>>
>>>>>on the same motherboard, a dual Xeon, with smp disabled all is OK
>>>>>with smp enabled restore gets stuck usualy waiting on biord.
>>>>>the iscsi driver shows that all requests have been done, the sniffing
>>>>>shows the same(ie all request have been done).
>>>>>
>>>>>so this leads me to think that there is some race condition that i'm not
>>>>>aware of in a SMP system, where xpt_done(ccb) is called while
>>>>>another process is calling biowait.
>>>>>
>>>>>another lead is that after restore gets stuck, the system slowly gets 
>>>>>'stalled'.
>>>>>
>>>>>any insight is most welcome!, i'm also stuck.
>>>>
>>>>
>>>>
>>>>ahh, hate talking to myself :-)
>>>>
>>>>grabbing Giant before calling xpt_done solved it, so the problem is
>>>>most probably in the CAM ...
>>>>
>>>>danny
>>>>
>>>>
>>>>
>>>
>>>No, you need to grab Giant when calling xpt_done().  I even put an
>>>assertion into CAM to make sure of that.  Are you running with WITNESS
>>>and/or INVARIANTS enabled?  Those would have caught this problem.
>>>
> 
> they are off :-(, would have saved me some time.
> 
>>>Scott
>>
>>Oops, I forgot to mention that I recently addressed this in 6-CURRENT.
>>Now, much of the rest of cam API still requires Giant to be held, but
>>xpt_done() does not.  This only applies to 6-CURRENT, and I doubt that
>>it will be backported to 5-STABLE.
>>
>>Scott
> 
> 
> so what you are saying is that in 5.x it's a must to grab Giant before calling
> xpt_done, and not in 6?
> 
> danny
> 
> 
> 

Correct.  Again, turning on WITNESS and INVARIANTS is a very good thing
to do during development.

Scott